Gold Powder from HCl-Cl + SMB

[lazersteve]

All,

Last night I processed some foils from a batch of AP with HCl-Cl followed by SMB and the gold powder came out very light colored without washing. The color of the solution was orange and took two additions of SMB to drop all the gold. I wanted to share these snapshots of the powder with the forum:

The above shot was taken of the powder dropped from the first addition of SMB.

This shot was taken of the powder dropped from the second addition of SMB.

I thought it was very unusual to see such strange colored gold powder (photo 1) dropped directly from auric chloride without washing. The second photo is more like what I'm used to seeing. The source material was memory fingers. The combined weight of the powders is 10.5 grams.

Steve

 

[dwt9999]

Steve,

Do you use anything to dry the powder or do you let it stay in the filter until dry?

Did you add more SMB right after filtering?

Lew

 

[lazersteve]

Lew,

The gold was dried as per Harolds instructions.

After washing the gold powder with three rinses of clean water I gently heated the gold powder in the same beaker it was dropped in until all the moisture was gone. I swirled the gold as it dried to keep it from sticking to the beaker. I only filter solutions of auric chloride now. I do not filter gold powder from any mixtures. The gold powder is triple rinsed and dried on low heat in the beaker.

Steve

 

[Harold_V]

Steve,

I'm pleased to see your results, and hope the tips I've provided have been beneficial.

I couldn't help but notice you comment on three rinses with water-----but no mention of the HCL wash that accompanies the process. I'm sure it's an oversight------but wanted to insure that it is understood to be a part of the washing process, along with one with ammonium hydroxide. It is the washing processes that tip the balance on gold quality, as you've likely come to understand.

It isn't uncommon for gold to precipitate very light in color as the solution improves in quality. You can expect even a light tan on occasion, depending on many variables, as I'm sure you've noticed.

It does my old heart good to see your quality coming up, Steve.

Harold